// Compiling cmd :
// cc hello_multithreads.c -o hello_multithreads -lpthread

#include <stdio.h>
#include <unistd.h>
#include <pthread.h>

#define NUM 5 

main(){
    pthread_t t1, t2 ;

    void * print_msg(void * ) ;
    pthread_create(&t1, NULL, print_msg, (void * )"hello");
    pthread_create(&t2, NULL, print_msg, (void *)"world\n");
    pthread_join(t1, NULL );
    pthread_join(t2, NULL );
}

void * print_msg(void * m){
    char * cp = (char * ) m ;
    int i ;
    for (i = 0 ; i < NUM; i ++){
        printf("%s", cp);
        fflush(stdout);
        sleep(1);
    }
    return NULL ;
}